As the video shows, they walked into a gorilla tracking camp and hung out a bit, even taking time to groom one of the humans (video producer John J. King II). That was, as the human sat quietly, amazed and probably scared a little out of his mind.

"It was an innocent interaction with wild gorillas," King says at the beginning, "and it was absolutely thrilling."

This looks a little like a tourism commercial ("Come see the wild mountain gorillas!"). But the creator says it's more than that.

The video has more than 2 million views on YouTube ... and it may be a good example of tourism helping preserve an endangered species. About half the world population of wild mountain gorillas (about 350) live in the National Park, according to UNESCO (the United Nations Educational Scientific and Cultural Organization).

"While gorilla tourism raises some risks, it just might be the animals' best chance for survival," according to National Geographic. There are concerns about changes in gorilla behavior due to human encounters and passing human diseases to gorillas, but also rules for gorilla tracking that include keeping a distance of 20 feet from the animals (if possible, apparently).